Relativity Lectures at Cambridge

I’ve just returned from one of the most interesting and insightful lecture series I have ever attended. They were mostly on special relativity, and, of course, in Cambridge. Lectures took place at the McCrum Lecture Theatre (Corpus Christi College), where Stephen Hawking recently unveiled the famous ‘Grasshopper Clock’:

Unfortunately reflections in the daytime, lack of a tripod at night and lack of patience on my part made it a difficult subject to photograph. It was built by the genius Dr John Taylor, and is entirely mechanical. Instead of hands it has lights which move round, but instead of using an array of LEDs, it’s actually a disc with 61 slits behind another disc with 60 slits. The entire thing is backlit, and by rotating the back disc slightly, slits on the front face appear to light up in quick succession, going round the face (clockwise) – a mechanism which, while probably actually rather common, I personally think is a work of engineering genius. The grasshopper at the top opens and closes its mouth while doubling up as an escapement mechanism – hence its name, the chronophage. Apparently it strikes hours by dropping a chain into a coffin, maybe in a metaphorical and literal attempt to ‘wake the dead’.

Dr Taylor’s genius extends also to the making of kettles: instead of using a spring-loaded switch or bimetallic strip, which owing to the high currents involved would not be ample to protect the switch from damage from electrical arcing, he came up with the wonderful idea of using a bimetallic dome, which, owing to the huge amounts of stress that would have to build up before it flips inside out (breaking the circuit), does so very quickly, reducing arcing to a minimum. Apparently he has now made a billion kettles, hence is presumably stinking rich, and deservedly so!

The lectures themselves were (fortunately) highly mathematical in nature. We explored the Lorentz factor in many of its different uses (t = yt’; x=(1/y)x0 etc… [super- and subscripts are hard in WordPress]), covering even areas such as the relativistic Doppler shift, simultaneity and Lorentz transformations, testing my Summer-holiday-decayed and sleep-deprived mathematical skills to the limit. What I was really pleased about was that we were encouraged to examine the proofs and algebra with rigour, making sure we understood the fundamentals before just sticking numbers into equations. And I finally got my question about the twins-paradox-in-reverse ‘paradox’ resolved!

We also started with some estimation problems – plugging estimated numbers into formulae to guess things like fuel efficiency of jumbo jets, resulting in very good examples of ‘garbage in garbage out’ situations. Later there was also a lecture on spin (cross products of vectors which my school disgracefully leaves until after GCSE to teach; angular momentum, torque, etc; and spin on particles such as electrons).

And not only were the lectures interesting, but the people who attended were some of the most inspiring, interesting and genuinely intelligent people I have ever met. They were (of course) all strong in Physics, Maths and general Sciences, and the academic atmosphere made for some really interesting discussions over lunch – mainly the rants of a fellow antitheist who somehow managed to reference the Casimir effect, Quantum Physics, Quantum tunnelling, M Theory and the multiverse theory in a 15-minute time interval without apparently stopping for breath while still making sense.

All in all, I found it a very worthwhile experience, and certainly a welcome break from performing titrations at school.

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This entry was posted on Monday, September 22nd, 2008 at 5:39 pm and is filed under Science. You can follow any responses to this entry through the RSS 2.0 feed.
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[…] and special relativity which spanned two days and included a night in a Corpus Christi apartment. I enthused about the whole experience and thought that would be the last I’d see of Cambridge before I apply next year. Then at the […]